1. Field of the Invention
The present invention relates to a method for forming a seat belt through-bore in an automotive seat, and particularly to the formation of such seat belt through bores in a bench-type seat cushion.
2. Description of Prior Art
Hitherto, the production of automotive seat assemblages involved bonding a top cover member to the surface of a foam cushion member, under a pressure, using an adhesive and a pair of upper and lower dies for that purpose. Such pressure bonding steps sometimes entail using a foam cushion member having a through-bore penetrated therethrough, and an associated cover member with a particular incision defined therein in correspondence with such through-bore of the cushion member. This is designed to permit a seat belt to pass through the seat. In most instances, the formation of seat belt through-bores is applied to such bench-type seat cushions (SC) as shown in FIG. 1.
However, referring to FIG. 2, the conventional method for forming the foregoing seat belt through-bore has encountered the problem of creating an undesired recession (1a) around the seat belt through-bore (H), which results in impairing the aesthetic appearance of the seat.
The reason for this problem is found attributed to certain steps in the conventional method, which will be explained with particular reference to FIGS. 3 and 4, as follows:
In FIG. 3;
Firstly, an upper die (U) and a lower die (L) are provided. The upper die (U) is movable vertically towards nd away from the lower die (L).
Then, between those upper and lower dies (U)(L), there is introduced a foam cushion member (2) having a pair of spaced-apart through-bores perforated therethrough of which one is shown in (21), each being in correspondence with the respective two resultant seat belt through-bores (H)(H) shown in FIG. 1, and a top cover member, (1) having a pair of spaced-apart incisions of which one is shown (7), each being also in correspondence with the respective two seat belt through-bores (H)(H). As shown, at each of those two incisions, of which only one is shown (7) of top cover member (1), there are provided a pair of covering pieces (3)(3) in a symmetrical fashion relative to one incision (7). Namely, the covering pieces (3)(3) are each made of the same material or cloth as that of the top cover member (1), and formed such as to have a width generally equal to the lengthwise width of each of the through-bores (21)(21) as can be seen from FIG. 2 as well as a length relatively longer than the height-wise thickness of cushion member (2). The two opposed ends respectively of thus-formed covering pieces (3)(3), as viewed from FIG. 3, are disposed at a point corresponding to the foregoing incision (7) of top cover member (1), and, in the vicinity of the incision (7) and the two opposed covering piece ends, each of the covering pieces (3)(3) is sewn to the upper surface of top cover member (1) at the respective points (5)(5). The distance between such sewn points (5)(5) should be generally identical with the width (W) of the through-bore (21).
Then, the thus-formed covering pieces (3)(3) are laid on and juxtaposed with the frontal surface of top cover member (1) as illustrated, and turned upside down to direct the reverse side of top cover member (1) in the upward direction, while directing both covering pieces (3)(3) and frontal side of top cover member (1) in the downward direction towards the upper surface of lower die (L). In this state, the top cover member (1) is placed upon the lower die (L). Next, an adhesive (4) is applied to the upper surface of cushion member (2) which is sought to be bonded to the reverse side of top cover member (1), and then the cushion member (2) is also turned upside down to direct its adhesive-applied upper surface in the downward direction towards the reverse side of top cover member (1) laid on the lower die, with a care being taken that the central axis of the through-bore (21) is substantially aligned with the incision (7) of top cover member (2).
Thereafter, the upper die (U) is lowered to press the cushion member (2) against the top cover member (1) on the lower die (L), so as to bond the reverse side of top cover member (1) to the upper surface of cushion member (2).
Next, as in FIG. 4;
The thus-bonded unit of top cover member (1) and cushion member (2) is again turned over, so that the frontal surface of top cover member (1) is directed upwardly, with the two covering pieces (3)(3) laying thereon as indicated by the two-dot chain lines in FIG. 4.
Then, the two covering pieces (3)(3) are turned about their respective sewn points (5)(5) and pulled down to extend through the through-bore (21) of cushion member (2), as indicated by the arrows in the same FIG. 4. The free ends respectively of the covering pieces (3)(3) are each anchored at the reverse side of cushion member (2) by means of insert wires and hog rings as shown. As a result, the seat belt through-bore (H) is formed, and a seat belt (6) may pass therethrough.
However, in the above-described steps, it is noticed that the two covering pieces (3) are pressed together with the top cover member (1) against the upper surface of foam cushion member (2) and consequently, after the pressure-bonding process using the upper and lower dies (U)(L), there is left an undesired recession (1a) upon the frontal surface of top cover member (1), tracing the shape of covering piece (3) thereon.